In pinball machines using pivotally mounted flippers, a relatively high power is required to move the flipper when the flipper switch is activated, while a much lower power is required to hold the flipper when the flipper is in the actuated position.
In one prior art pinball flipper circuit, the solenoid coil which operates the pinball flipper comprises two windings in series. One winding serves to provide a strong pull on the selenoid coil for the power stroke and a second "holding" winding serves to hold the flipper in the actuated position. This arrangement was considered necessary since a single coil winding was not considered capable of both high power and continuous operation. When the flipper is at rest, a normally closed "end of stroke" switch bypasses the holding winding, leaving only the power winding in the circuit. When the flipper is actuated, the power winding is active throughout the mechanical stroke until, at the end of travel, the flipper mechanism opens the end of stroke switch and places the low power holding winding in the circuit. This arrangement requires that the flipper switch and the end of stroke switch break a high current circuit with resulting arcing and contact wear. The high current levels required also necessitate the use of a relay to enable or disable the flipper circuits under control of the game logic.
In Powers U.S. Pat. No. 4,384,716, a flipper control circuit is disclosed in which a full wave rectified voltage is applied to the solenoid coil when a flipper switch is activated, to place the flipper in an actuated position. When the flipper has been sensed to be in the actuated position, only a partial phase control voltage is applied to the solenoid coil to hold the flipper in the actuated position until the flipper switch is deactivated.
In Deger U.S. Pat. No. 4,790,536, the solenoid for controlling the flipper includes low and high resistance coils placed in electrically parallel relationship across a source of electrical energy upon activation of the flipper switch. At the end of the travel of the flipper, the end of stroke switch automatically removes electrical energy from the low resistance coil and leaves only the high resistance coil energized to hold the flipper in position.
I have discovered a novel flipper control circuit which obviates the need for a dual coil solenoid, is simple in operation and is efficient to manufacture.